The disclosed embodiments relate to three-dimensional semiconductor memory devices, and in particular, to three-dimensional semiconductor memory devices with improved reliability and a higher integration density.
Higher integration of semiconductor devices satisfies consumer demands for superior performance and inexpensive prices. In the case of semiconductor devices, since their integration is an important factor in determining product prices, increased integration is especially valuable. In the case of typical two-dimensional or planar semiconductor memory devices, since their integration is mainly determined by the area occupied by a unit memory cell, integration is greatly influenced by the level of a fine pattern forming technology. However, the extremely expensive process equipment needed to increase pattern fineness sets a practical limitation on increasing integration for two-dimensional or planar semiconductor devices. To overcome such a limitation, there have been recently proposed three-dimensional semiconductor memory devices including three-dimensionally arranged memory cells.